Requirements

The modern view of an atom consists of a nucleus made from protons and neutrons with electrons surrounding it in regions of high probability called orbitals. In this activity, students build computer models of atoms by adding and removing electrons, protons, and neutrons.

AAAS Benchmark Alignments (2008)

1. The Nature of Science

1A. The Scientific Worldview

1A/H2*. By the end of the 12th grade, students should know that from time to time, major shifts occur in the scientific view of how things work. More often, however, the changes that take place in the body of scientific knowledge are small modifications of prior knowledge. Continuity and change are persistent features of science.

4. The Physical Setting

4D. The Structure of Matter

4D/H1*. By the end of the 12th grade, students should know that atoms are made of a positively charged nucleus surrounded by negatively charged electrons. The nucleus is a tiny fraction of the volume of an atom but makes up almost all of its mass. The nucleus is composed of protons and neutrons which have roughly the same mass but differ in that protons are positively charged while neutrons have no electric charge.

4D/H2*. By the end of the 12th grade, students should know that the number of protons in the nucleus determines what an atom's electron configuration can be and so defines the element. An atom's electron configuration, particularly the outermost electrons, determines how the atom can interact with other atoms. Atoms form bonds to other atoms by transferring or sharing electrons.

4D/H3*. By the end of the 12th grade, students should know that although neutrons have little effect on how an atom interacts with other atoms, the number of neutrons does affect the mass and stability of the nucleus. Isotopes of the same element have the same number of protons (and therefore of electrons) but differ in the number of neutrons.

4G. Forces of Nature

4G/H3*. By the end of the 12th grade, students should know that most materials have equal numbers of protons and electrons and are therefore electrically neutral. In most cases, a material acquires a negative charge by gaining electrons and acquires a positive charge by losing electrons. Even a tiny imbalance in the number of protons and electrons in an object can produce noticeable electric forces on other objects.

11. Common Themes

11B. Models

11B/M1*. By the end of the 8th grade, students should know that models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly. They are also used for processes that are too vast, too complex, or too dangerous to study.

11B/H1a*. By the end of the 12th grade, students should know that a mathematical model uses rules and relationships to describe and predict objects and events in the real world.

11D. Scale

11D/M3**. By the end of the 8th grade, students should know that natural phenomena often involve sizes, durations, and speeds that are extremely small or extremely large. These phenomena may be difficult to appreciate because they involve magnitudes far outside human experience.

A Note about Java and Security

Our goal is for teachers and students to have a successful experience with our software. Some of our activities require Java software to be enabled on your computer. Due to recent security problems found in Java, we recommend upgrading to the latest version of Java before using our software.

We are evaluating options for ensuring that users can easily run our software without installing additional updates. Bulletins and updates on Java security: